It is well known in the oil and gas industry that produced oil will contain at least a small fraction of hydrocarbon chains of asphaltene or paraffin which upon thermodynamic changes caused by production may lead to deposits which are commonly referred to as wax. This wax is a soft solid that forms on the inside of production tubing, surface flow lines, valves and tank bottoms. It can even form at the perforations and inside of the formation especially near the wellbore. The change in state to a soft solid is usually caused by a decrease in temperature and/or decrease in pressure of the produced hydrocarbons as they flow from the formation to the surface. These thermodynamic transitions, for example, can cause the suspended asphaltene to flocculate and cause the longer chain paraffins to phase change causing congealing.
Wax formation occurs in every oil well in the world to some degree and in the extreme cases will completely plug off production tubing. In particular these issues are of everyday concern for offshore crude flow assurance and heavy wax crudes such as those found in Utah. To date there have been many methods used to deal with this complicated problem. A U.S. Department of Commerce, Bureau of Mines report from 1932 (Bulletin 348, titled “Paraffin and Congealing-Oil Problems with a Chapter on a Laboratory Study of Wax Rods” by C. E. Reistle Jr. and O. C. Blade) shows that this has been a problem for well over 100 years and provides many solutions from that era divided into three main groups: 1) Mechanical removal such as scrapers, reamers, hydraulic methods, compressed air and explosives, 2) Solvents such as gasoline and kerosene, 3) Heat such as steam, hot water, hot gas, hot oil (all heated on surface), heat forming chemicals (combinations noted are lye/aluminum/water, calcium carbide/water and sodium peroxide/water), flame (similar to fire flooding) and electric heaters. A more recent summary of paraffin removal methods are described in sufficient detail in a 2003 conference paper by K. M. Barker, et al., SPE80903 “Cost—Effective Treatment Programs for Paraffin Control”. The treatments are: Hot Oiling, Hot Watering, Cutting or Wire Lining, Pigging, Solvent or Condensate, Chemicals. The paper goes on to describe that the Hot Oiling and Hot Watering treatments are only effective for deposits that are no deeper than 150-300 m (˜500-1000 ft) below the surface because the oil or water is made hot on the surface and then pumped down hole loosing energy to the earth hence limiting the depth of usefulness.
Hence to solve this problem in existing and ever deeper wells what is needed is a method to safely produce energy in the form of heat where it is needed: down hole and at depths greater than 300 m (˜1,000 ft) and as far as the drill bit can go, for example. In addition the oil and gas industry has been reaching deeper and ever deeper for hydrocarbons in some cases over 9150 m (˜30,000 ft).
The present disclosure discloses inter alia a method whereby a liquid oxidizer can be safely delivered to any presently known depth that a liquid fuel may also be delivered. There does exist prior methods for delivery of liquid oxidizers to bottom hole locations. Smith teaches a method to deliver hydrogen peroxide (U.S. Pat. No. 8,047,285 and U.S. patent application Ser. No. 12/424,376 and Ser. No. 13/028,883). The present disclosure is superior to this prior method that utilizes hydrogen peroxide, for example, in that hydrogen peroxide can create oil field hazards by several means. The primary of these hazards being that oxygen is produced by decomposing the hydrogen peroxide. From which, if the system is improperly operated, such produced oxygen may form a combustive/explosive mixture with methane either down hole or in the production lines. While the intention would be to consume all of this oxygen, an explosion hazard is still present and must be accounted for. Example embodiments of the present disclosure utilize what is known to those in the art as a “selective oxidizer,” or an oxidizer that will only be made to react with particular compounds and ignore or greatly reduce reaction with others. This disclosure teaches example embodiments using a selective oxidizer composition that is non-selective with respect to alkane chemistry. The use of non-alkane selective oxidizer use greatly increases the safe operation in a fuel rich environment, such as a hydrocarbon reservoir, given that almost all produced hydrocarbons are of alkane chemistry. In addition, in certain aspects of the aforementioned Smith patents and applications (U.S. Pat. No. 8,047,285 and U.S. patent application Ser. No. 12/424,376 and Ser. No. 13/028,883) make use of energy release from decomposition of hydrogen peroxide using a catalyst whereas the present disclosure does not require the presence of catalyst for reaction and heat release.